pfft and p3dfft are specialized in computing FFT efficiently
on several cores of big clusters. The data is spit in pencils and can be
distributed on several processes.

Fluidfft provides an uniform API for all these libraries. Fluidfft can be used
for example as a base to write pseudo-spectral simulation codes. In particular,
fluidfft is used in the code fluidsim. Fluidfft also provides classes to
efficiently perform linear operators (gradient, divergence, rotational, etc.)
and easily deal with the data distribution (gather the data on one process,
scatter the data to many processes).